Simplify the following expression: $q = \dfrac{y}{2} - \dfrac{y}{5}$
In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $2$ and $5$ $\lcm(2, 5) = 10$ $ q = \dfrac{5}{5} \cdot \dfrac{y}{2} - \dfrac{2}{2} \cdot \dfrac{y}{5} $ $q = \dfrac{5y}{10} - \dfrac{2y}{10}$ $q = \dfrac{5y -2y}{10}$ $q = \dfrac{3y}{10}$